Compositions comprising 1,1-difluoroethene, trifluoromethane and a third component

ABSTRACT

The present invention provides a composition, such as a refrigerant composition comprising 1, 1-difluoroethene (vinylidene fluoride, R-1132a); trifluoromethane (R-23); and one or more compound selected from hexafluoroethane (R-116), ethane (R-170) and carbon dioxide (R-744, CO 2 ).

The invention relates to compositions, preferably to heat transfercompositions, and in particular to ultra-low temperature heat transfercompositions which may be suitable as replacements for existingrefrigerants such as R-508A, R-508B, R-23 or R-13B1.

The listing or discussion of a prior-published document or anybackground in the specification should not necessarily be taken as anacknowledgement that a document or background is part of the state ofthe art or is common general knowledge.

Mechanical refrigeration systems and related heat transfer devices suchas heat pumps and air-conditioning systems are well known. In suchsystems, a refrigerant liquid evaporates at low pressure taking heatfrom the surrounding zone. The resulting vapour is then compressed andpassed to a condenser where it condenses and gives off heat to a secondzone, the condensate being returned through an expansion valve to theevaporator, so completing the cycle. Mechanical energy required forcompressing the vapour and pumping the liquid is provided by, forexample, an electric motor or an internal combustion engine.

Certain refrigerant applications, notably biomedical refrigeration, uselow-boiling refrigerant gases to achieve cooling of materials, typicallyto temperatures of about −85° C. or below. These fluids are sometimesreferred to as ultra-low temperature (ULT) or cryogenic refrigerants.

The most commonly used non-flammable ULT refrigerants currently areR-508A and R-508B. The term R-508 is used herein to refer to R-508A andR-508B, which are both mixtures of trifluoromethane (R-23) withhexafluoroethane (R-116) and are rated A1 by the ASHRAE Standard 34classification.

Typical low-temperature applications of R-508 fluids are normallycascade systems: a first vapour compression refrigeration cycle coolsair inside a refrigerated compartment to between about −80 and −95° C.by evaporation of liquid R-508. The gaseous refrigerant is thencompressed and condensed in a heat exchanger, where it vaporises asecond refrigerant (for example R-404A). A typical condensingtemperature for R-508 in this exchanger is in the range −50 to −30° C.,typically about 40° C. The second refrigerant vapour is compressed by asecond compressor and is then condensed against ambient air.

The greenhouse (or global) warming potential (GWP) of low boilingnon-flammable refrigerant gases such as R-508 or R-23 is high (e.g.about 13000), and it is desired to find fluids able to be used in thisapplication with lower GWP, so as to reduce the environmental impact ofrefrigerant leakage.

In looking for alternative low temperature refrigerants several otherfactors must also be considered. Firstly, if the fluid is to be used asa retrofit or conversion fluid in existing equipment, or as a “drop-in”to new equipment using an essentially unchanged R-508 system design,then non-flammability is highly desired, as the existing design willhave been based on the use of non-flammable fluid.

If an alternative fluid is to be employed in a wholly new system designthen a degree of flammability may be tolerable; but the use of highlyflammable fluids may impose cost and performance penalties to mitigatehazards. Acceptable charge size (refrigerant mass) in a system is alsogoverned by the flammability classification of the fluid, with class 3fluids, such as ethane, being the most strictly limited. In this case aweaker flammability characteristic is highly desirable since it mayallow larger system charges.

Thirdly, the typical application of such fluids is in commercial orlaboratory based equipment and so the systems will be located inbuildings. It is therefore desirable to have acceptably low toxicity asa characteristic of the fluid.

Furthermore, the volumetric capacity (a measure of the cooling powerachievable by a given size of compressor) and energy efficiency areimportant. This is especially so in cascade operation as inefficiency inthe low temperature stage also increases power consumption of thecompressor in the top stage of the cascade.

R-170 (ethane) has very low GWP, acceptable refrigeration performanceand toxicity but its high flammability limits its application: forexample safety regulations can restrict the maximum charge quantity ofrefrigerant in appliances.

Binary mixtures of R-170 with R-116 have been described by Zhang et al.(J Chem Eng Data 2005 50 2074-2076 and Fluid Phase Equilibria 2006 24073-78). They identified an azeotropic binary composition of these twocomponents.

R-744 (carbon dioxide) is non-flammable but cannot be used alone in thebottom stage of ULT cascade systems because the operating temperaturesare below the triple point of R-744. This means that solid carbondioxide (dry-ice) could form in low pressure sections of the system,leading to blockages, poor control and inefficient operation.

Binary mixtures of R-744 with R-116 have been described by Valtz et al(Fluid Phase Equilibria 258 (2007) 179-185). They identified anazeotropic binary composition of these two components.

R-1132a (1,1-difluoroethene, also known as vinylidene fluoride) also haslow GWP and acceptable toxicity. The flammability of R-1132a is reducedcompared to ethane but it is still in flammability class 2. U.S. Pat.No. 6,054,064 describes the use of R-1132a in certain refrigerantcompositions including mixtures with R-23, R-32, R-125, R-134a andR-143a. The thermodynamic energy efficiency of pure R-1132a is close tothat of R-508 but its refrigeration capacity is reduced.

Thus there is a need to provide alternative refrigerants having improvedproperties such as low GWP, yet possessing acceptable refrigerationperformance, flammability characteristics and toxicology. There is alsoa need to provide alternative refrigerants that may be used in existingdevices such as refrigeration devices with little or no modification.

The subject invention addresses the above and other deficiencies by theprovision of a composition comprising 1,1-difluoroethene (vinylidenefluoride, R-1132a), trifluoromethane and one or more compounds selectedfrom hexafluoroethane (R-116), ethane (R-170) and carbon dioxide (R-744,CO₂).

Also provided is the use of the compositions of the invention asrefrigerants, preferably ultra-low temperature refrigerants. Theultra-low temperatures reached by the compositions of the invention maybe −70° C. or below, such as −80° C. or below, preferably −85° C. orbelow, or even −90° C. or below.

Surprisingly, it has been found that the compositions of the inventionexhibit further enhanced refrigeration capacities compared to R-23 andreduced flammability compared to R-1132a.

Compositions of the invention may comprise:

-   -   i) 1,1-difluoroethene (vinylidene fluoride, R-1132a);    -   ii) trifluoromethane (R-23); and    -   iii) one or more compound selected from hexafluoroethane (R-116)        and/or ethane (R-170); and    -   iv) carbon dioxide (R-744, CO₂).

In an embodiment, compositions of the invention comprise:

-   -   i) 1,1-difluoroethene (vinylidene fluoride, R-1132a);    -   ii) trifluoromethane (R-23); and    -   iii) one or more compound selected from hexafluoroethane (R-116)        and/or ethane (R-170); and    -   iv) less than about 50% by weight carbon dioxide (R-744, CO₂).

The compositions of the invention may contain about 15% by weight orless of carbon dioxide, such as about 10% by weight or less carbondioxide.

Advantageously, compositions of the invention may comprise from about 1to about 98% by weight R-1132a and/or from about 1 to about 98% byweight R-23.

Preferably the compositions may contain from about 35 to about 95% byweight R-1132a, such as from about 35 to about 90% by weight, from about35 to about 85% by weight R-1132a, or from about 37 to about 80% byweight R-1132. Even more preferably the compositions may comprise fromabout 40 to about 60% by weight R-1132a.

Advantageously, compositions may contain from about 1 to about 90% byweight R-23, such as from about 1 to about 75% by weight R-23, e.g. fromabout 60 to about 70% by weight R-23 or from about 1 to about 40% byweight R-23. Composition of the invention may contain from about 1 toabout 30% by weight R-23, such as from about 1 to about 25% by weightR-23 or from about 5 to about 25% by weight R-23, from about 7 to about22% by weight R-23 or from about 1 to about 20% by weight R-23.

Preferably, compositions may comprise up to about 80% by weight R-116,such as from about 1 to about 60% by weight R-116. Even more preferably,the compositions may comprise from about 1 to about 50% by weight, suchas from about 1 to about 40% by weight R-116, from about 1 to about 30%by weight R-116, or from about 5 to about 25% by weight R-116.

Preferably, compositions comprise from greater than zero to about 40% byweight R-116, from about 5 to about 98% by weight R-1132a and from about5 to about 98% by weight R-23; such as from about 1 to about 30% (e.g.from about 1 to about 15%) by weight R-116, from about 20 to about 90%(e.g. from about 35 to about 60%) by weight R-1132a and from about 5 toabout 95% (e.g. from about 20 to about 50%) by weight R-23.

Advantageous compositions comprise from about 1 to about 25% by weightR-116, from about 30 to about 80% by weight R-1132a and from about 5 toabout 90% by weight R-23.

Preferably, compositions comprise from about 1 to about 20% by weightR-116, from 40 to about 80% by weight and from about 5 to about 30% byweight R-23. Alternatively, compositions may contain from about 1 toabout 20% by weight R-116, from about 40 to about 60% by weight R-1132aand from about 50 to about 70% by weight R-23.

Advantageously, compositions may comprise from about 1 to about 15% byweight R-116, from about 45 to about 60% by weight R-1132a and fromabout 1 to about 25% by weight R-23.

In an embodiment, the compositions of the invention comprise up to about40% by weight R-170, preferably from about 1 to about 30% by weightR-170.

Advantageously, the compositions of the invention may comprise fromabout 1 to about 25% by weight R-170, such as from about 5 to about 25%by weight.

Preferably, compositions comprise from about 1 to about 40% by weightR-170, from about 5 to about 98% by weight R-1132a and from about 5 toabout 98% by weight R-23; such as from about 1 to about 30% by weightR-170, from about 20 to about 90% by weight R-1132a and from about 5 toabout 95% by weight R-23

Advantageous compositions comprise from about 1 to about 25% by weightR-170, from about 30 to about 80% by weight R-1132a and from about 5 toabout 90% by weight R-23.

Preferably, compositions comprise from about 1 to about 20% by weightR-170, from 40 to about 80% by weight and from about 5 to about 30% byweight R-23. Alternatively, compositions may contain from about 1 toabout 15% by weight R-170, from about 40 to about 60% by weight R-1132aand from about 50 to about 70% by weight R-23.

Advantageously, compositions may comprise from about 1 to about 10% byweight R-170, from about 45 to about 60% by weight R-1132a and fromabout 1 to about 25% by weight R-23.

In an aspect of the invention, the compositions do not contain, or aresubstantially free of, carbon dioxide.

In an alternative aspect, the composition of the invention may containfrom about 1 to about 45% by weight carbon dioxide, such as from about 1to about 35% by weight carbon dioxide, preferably from about 1 to about30% by weight carbon dioxide, even more preferably from about 1 to about15% by weight carbon dioxide, or even from about 1 to about 10% byweight carbon dioxide.

Preferably, compositions comprise from about 35 to about 95% by weightR-1132a, from about 1 to about 75% by weight R-23, from about 1 to about60% by weight R-116 and from about 1 to about 35% by weight carbondioxide.

Advantageously, compositions comprise from about 30 to about 85% byweight R-1132a, from about 1 to about 40% by weight R-23 and from about1 to about 15% by weight carbon dioxide.

Preferably, compositions comprise from about 40 to about 70% by weightR-1132a, from about 1 to about 30% by weight R-23 and from about 1 toabout 10% by weight carbon dioxide; such as from about 45 to about 70%by weight R-1132a, from about 1 to about 25% by weight R-23 and fromabout 1 to about 7% by weigh carbon dioxide, or even from about 45 toabout 70% by weight R-1132a, from about 1 to about 25% by weight R-23and from about 1 to about 5% by weigh carbon dioxide.

In an embodiment, the composition of invention comprise both R-116 andR-170. Preferably, the composition comprises R-116 and R-170 in theamounts specified above.

In an embodiment, the compositions may contain from about 35 to about95% by weight R-1132a, from about 1 to about 75% by weight R-23, fromabout 1 to about 50% by weight R-116 and from about 1 to about 40% byweight R-170.

Preferably, the compositions comprise from about 35 to about 70% byweight R-1132a, from about 1 to about 40% by weight R-23, from about 1to about 40% by weight R-116 and from about 1 to about 30% by weightR-170; such as from about 40 to about 70% by weight R-1132a, from about1 to about 30% by weight R-23, from about 1 to about 30% by weight R-116and from about 1 to about 15% by weight R-170.

In an embodiment, the compositions comprise from about 35 to about 95%by weight R-1132a, from about 1 to about 75% by weight R-23, from about1 to about 50% by weight R-116 and from about 1 to about 40% by weightcarbon dioxide.

Preferably, the compositions comprise from about 35 to about 70% byweight R-1132a, from about 1 to about 40% by weight R-23, from about 1to about 40% by weight R-116 and from about 1 to about 15% by weightcarbon dioxide; such as from about 40 to about 70% by weight R-1132a,from about 1 to about 30% by weight R-23, from about 1 to about 30% byweight R-116 and from about 1 to about 10% by weight R-170.

In an embodiment, the compositions comprise from about 35 to about 95%by weight R-1132a, from about 1 to about 75% by weight R-23, from about1 to about 30% by weight R-170 and from about 1 to about 40% by weightcarbon dioxide.

Preferably, the compositions comprise from about 35 to about 70% byweight R-1132a, from about 1 to about 40% by weight R-23, from about 1to about 20% by weight R-170 and from about 1 to about 15% by weightcarbon dioxide.

Preferably, the compositions comprise from about 40 to about 70% byweight R-1132a, from about 1 to about 30% by weight R-23, from about 1to about 10% by weight R-170 and from about 1 to about 10% by weightR-170.

In an embodiment, the composition comprises R-1132a, R-23, R-116, R-170and carbon dioxide.

In some preferred embodiments, the composition comprises about 1 toabout 98% by weight R-1132a, about 1 to about 98% by weight R-23 andabout 1 to about 50% by weight carbon dioxide. For example, thecomposition may comprise about 35 to 98% by weight R-1132a, about 1 toabout 60% by weight R-23 and about 1 to about 20% by weight carbondioxide. In some of these embodiments, the composition may compriseabout 40 to about 60% by weight R-23, for example about 45 to about 55%by weight R23. It is preferred that any of such compositions compriseabout 4 to about 16% by weight carbon dioxide.

Any of the above described compositions may further contain ahydrocarbon, wherein the hydrocarbon is in addition to any ethanepresent in the composition. Advantageously, the hydrocarbon is one ormore compound(s) selected from the group consisting of propane, propene,isobutane, n-butane, n-pentane, isopentane and mixtures thereof. In apreferred embodiment, the hydrocarbon comprises n-pentane.

Without being bound by theory, it is believed that, when present, theinclusion of ethane and/or an additional hydrocarbon compound mayenhance oil miscibility, solubility and/or return characteristics.Preferably, the compositions of the invention preferably contain fromabout 1 to about 50% by weight of the hydrocarbon component, for examplefrom about 1 to about 20%.

In an embodiment, the compositions may consist essentially of the statedcomponents.

By the term “consist essentially of”, we mean that the compositions ofthe invention contain substantially no other components, particularly nofurther (hydro)(fluoro)compounds (e.g. (hydro)(fluoro)alkanes or(hydro)(fluoro)alkenes) known to be used in heat transfer compositions.The term “consist of” is included within the meaning of “consistessentially of”.

In an embodiment, the compositions of the invention are substantiallyfree of any component that has heat transfer properties (other than thecomponents specified). For instance, the compositions of the inventionmay be substantially free of any other hydrofluorocarbon compound.

By “substantially no” and “substantially free of”, we include themeaning that the compositions of the invention contain 0.5% by weight orless of the stated component, preferably 0.1% or less, based on thetotal weight of the composition.

The compositions of the invention may be azeotropic.

By azeotropic composition, we include the meaning of a composition whichat vapour-liquid equilibrium has the same composition in both phases,and whose boiling point is lower than that of the pure components, Allthe azeotropic compositions of the invention have been found to exhibita positive deviation from ideality. By near-azeotropic composition weinclude the meaning of liquid compositions whose vapour pressure isabove that of the pure component with the lower boiling point whenmeasured at equivalent temperature, but whose equilibrium vapourcomposition may differ from the liquid composition.

All of the chemicals herein described are commercially available. Forexample, the fluorochemicals may be obtained from Apollo Scientific (UK)and carbon dioxide may be obtained from liquefied gas suppliers such asLinde AG.

As used herein, all % amounts mentioned in compositions herein,including in the claims, are by weight based on the total weight of thecompositions, unless otherwise stated.

By the term “about”, as used in connection with numerical values ofamounts of components in % by weight, we include the meaning of ±0.5% byweight, for example ±0.2% by weight or ±0.1% by weight.

For the avoidance of doubt, it is to be understood that the stated upperand lower values for ranges of amounts of components in the compositionsof the invention described herein may be interchanged in any way,provided that the resulting ranges fall within the broadest scope of theinvention.

The compositions of the invention have zero ozone depletion potential

Typically, the compositions of the invention have a GWP of less thanabout 12000, such as less than about 11000.

In one embodiment, the compositions of the invention have a GWP of lessthan about 11000, preferably less than about 10500 or about 10000 orabout 9000 or about 8000.

In one aspect, the compositions of the invention comprising R-1132a,R-116 and R-23 have a GWP of less than about 11000, for instance lessthan about 10000, e.g. from about 100 to about 10000, or from about 100to about 7000

In one embodiment, the compositions of the invention comprising R-1132a,R-23, R-116 and CO₂ have a GWP of less than about 10000, for instanceless than about 9000, e.g. from about 1000 to about 8000, or from about2000 to about 7000.

Typically, the compositions of the subject invention are of reducedflammability hazard when compared to R-1132a.

Flammability may be determined in accordance with ASHRAE Standard 34incorporating the ASTM Standard E-681 with test methodology as perAddendum 34p dated 2004, the entire content of which is incorporatedherein by reference.

In some embodiments, the compositions have one or more of (a) a higherlower flammable limit; (b) a higher ignition energy (sometimes referredto as auto ignition energy or pyrolysis); or (c) a lower flame velocitycompared to R-1132a alone. Preferably, the compositions of the inventionare less flammable compared to R-1132a in one or more of the followingrespects: lower flammable limit at 23° C.; lower flammable limit at 60°C.; breadth of flammable range at 23° C. or 60° C.; auto-ignitiontemperature (thermal decomposition temperature); minimum ignition energyin dry air or flame speed. The flammable limits being determinedaccording to the methods specified in ASHRAE-34 and the auto-ignitiontemperature being determined in a 500 ml glass flask by the method ofASTM E659-78.

In a preferred embodiment, the compositions of the invention arenon-flammable. For example, the compositions of the invention arenon-flammable at a test temperature of 60° C. using the ASHRAE-34methodology. Advantageously, the mixtures of vapour that exist inequilibrium with the compositions of the invention at any temperaturebetween about −20° C. and 60° C. are also non-flammable.

In some applications it may not be necessary for the formulation to beclassed as non-flammable by the ASHRAE-34 methodology; it is possible todevelop fluids whose flammability limits will be sufficiently reduced inair to render them safe for use in the application, for example if it isphysically not possible to make a flammable mixture by leaking therefrigeration equipment charge into the surrounds.

In one embodiment, the compositions of the invention have a flammabilityclassifiable as 1 or 2L according to the ASHRAE standard 34classification method, indicating non-flammability (class 1) or a weaklyflammable fluid with flame speed lower than 10 cm/s (class 2L).

A composition of the invention preferably have a temperature glide in anevaporator or condenser of less than about 10 K, even more preferablyless than about 5 K, such as less than about 1 K.

The critical temperature of a heat transfer composition should be higherthan the maximum expected condenser temperature. This is because thecycle efficiency drops as critical temperature is approached. As thishappens, the latent heat of the refrigerant is reduced and so more ofthe heat rejection in the condenser takes place by cooling gaseousrefrigerant; this requires more area per unit heat transferred. Thecritical temperature of R-508B is about 11° C. (data estimated byREFPROP).

In one aspect, the compositions of the invention have a criticaltemperature of greater than about 0° C., preferably greater than about10° C.

It is believed that the compositions of the invention exhibit acompletely unexpected combination of low-/non-flammability, low GWP,improved lubricant miscibility and improved refrigeration performanceproperties. Some of these refrigeration performance properties areexplained in more detail below.

The compositions of the invention typically have a volumetricrefrigeration capacity that is at least 85% of that of R-508 atcomparable cycle conditions. Preferably, the compositions of theinvention have a volumetric refrigeration capacity that is at least 90%of that of R-508, for example from about 95% to about 120% of that ofR-508.

The compositions of the invention typically are capable of reachingtemperatures of −70° C. or lower, preferably −80° C. or lower, forexample −85° C. or lower whilst maintaining the evaporation pressureabove atmospheric pressure.

In one embodiment, the cycle efficiency (Coefficient of Performance,COP) of the compositions of the invention is within about 5% or evenbetter than the existing refrigerant fluid it is replacing.Conveniently, the compressor discharge temperature of the compositionsof the invention is within about 15 K of the existing refrigerant fluidit is replacing, preferably about 10 K or even about 5 K.

The compositions of the invention are typically suitable for use inexisting designs of equipment, for example, ULT refrigeration equipmentand are compatible with all classes of lubricant currently used withestablished HFC refrigerants. They may be optionally stabilised orcompatibilised with mineral oils by the use of appropriate additives.

Preferably, when used in heat transfer equipment, the composition of theinvention is combined with a lubricant.

Conveniently, the lubricant is selected from the group consisting ofmineral oil, silicone oil, polyalkyl benzenes (PABs), polyol esters(POEs), polyalkylene glycols (PAGs), polyalkylene glycol esters (PAGesters), polyvinyl ethers (PVEs), poly (alpha-olefins) and combinationsthereof. PAGs and POEs are currently preferred lubricants for thecompositions of the invention.

Advantageously, the lubricant further comprises a stabiliser.

Preferably, the stabiliser is selected from the group consisting ofdiene-based compounds, phosphates, phenol compounds and epoxides, andmixtures thereof.

Conveniently, the composition of the invention may be combined with aflame retardant.

Advantageously, the flame retardant is selected from the groupconsisting of tri-(2-chloroethyl)-phosphate, (chloropropyl) phosphate,tri-(2,3-dibromopropyl)-phosphate, tri-(1,3-dichloropropyl)-phosphate,diammonium phosphate, various halogenated aromatic compounds, antimonyoxide, aluminium trihydrate, polyvinyl chloride, a fluorinatediodocarbon, a fluorinated bromocarbon, trifluoro iodomethane,perfluoroalkyl amines, bromo-fluoroalkyl amines and mixtures thereof.

In one embodiment, the invention provides a heat transfer devicecomprising a composition of the invention.

Preferably, the heat transfer device is a refrigeration device.

Conveniently, the heat transfer device is an ultra-low temperaturerefrigeration system.

Advantageously, the heat transfer device contains a cascade system.

The invention also provides the use of a composition of the invention ina heat transfer device as herein described.

According to another aspect of the invention, there is provided asprayable composition comprising a material to be sprayed and apropellant comprising a composition of the invention.

According to a further aspect of the invention, there is provided amethod for cooling an article which comprises condensing a compositionof the invention and thereafter evaporating said composition in thevicinity of the article to be cooled.

According to another aspect of the invention, there is provided a methodfor heating an article which comprises condensing a composition of theinvention in the vicinity of the article to be heated and thereafterevaporating said composition.

According to a further aspect of the invention, there is provided amethod for extracting a substance from biomass comprising contacting thebiomass with a solvent comprising a composition of the invention, andseparating the substance from the solvent.

According to another aspect of the invention, there is provided a methodof cleaning an article comprising contacting the article with a solventcomprising a composition of the invention.

According to a further aspect of the invention, there is provided amethod for extracting a material from an aqueous solution comprisingcontacting the aqueous solution with a solvent comprising a compositionof the invention, and separating the material from the solvent.

According to another aspect of the invention, there is provided a methodfor extracting a material from a particulate solid matrix comprisingcontacting the particulate solid matrix with a solvent comprising acomposition of the invention, and separating the material from thesolvent.

According to a further aspect of the invention, there is provided amechanical power generation device containing a composition of theinvention.

Preferably, the mechanical power generation device is adapted to use aRankine Cycle or modification thereof to generate work from heat.

According to another aspect of the invention, there is provided a methodof retrofitting a heat transfer device comprising the step of removingan existing heat transfer fluid, and introducing a composition of theinvention. Preferably, the heat transfer device is a refrigerationdevice, more preferably still the device is an ultra-low temperaturerefrigeration system. Preferably, the refrigeration system cools acompartment to less than about −70° C., preferably less than about −80°C., for example to less than −85° C., or even less than −90° C.

Advantageously, the method further comprises the step of obtaining anallocation of greenhouse gas (e.g. carbon dioxide) emission credit.

In accordance with the retrofitting method described above, an existingheat transfer fluid can be fully removed from the heat transfer devicebefore introducing a composition of the invention. An existing heattransfer fluid can also be partially removed from a heat transferdevice, followed by introducing a composition of the invention.

The compositions of the invention may also be prepared simply by mixingthe R-1132a, R-23 (and further components such as R-116, R-170, R-744,hydrocarbons, a lubricant, a stabiliser or an additional flameretardant) in the desired proportions. The compositions can then beadded to a heat transfer device (or used in any other way as definedherein).

In a further aspect of the invention, there is provided a method forreducing the environmental impact arising from operation of a productcomprising an existing compound or composition, the method comprisingreplacing at least partially the existing compound or composition with acomposition of the invention. Preferably, this method comprises the stepof obtaining an allocation of greenhouse gas emission credit.

By environmental impact we include the generation and emission ofgreenhouse warming gases through operation of the product.

As mentioned above, this environmental impact can be considered asincluding not only those emissions of compounds or compositions having asignificant environmental impact from leakage or other losses, but alsoincluding the emission of carbon dioxide arising from the energyconsumed by the device over its working life. Such environmental impactmay be quantified by the measure known as Total Equivalent WarmingImpact (TEWI). This measure has been used in quantification of theenvironmental impact of certain stationary refrigeration and airconditioning equipment, including for example supermarket refrigerationsystems (see, for example,http://en.wikipedia.org/wiki/Total_equivalent_warming_impact).

The environmental impact may further be considered as including theemissions of greenhouse gases arising from the synthesis and manufactureof the compounds or compositions. In this case the manufacturingemissions are added to the energy consumption and direct loss effects toyield the measure known as Life-Cycle Carbon Production (LCCP, see forexample http://www.sae.org/events/aars/presentations12007papasavva.pdf).The use of LCCP is common in assessing environmental impact ofautomotive air conditioning systems.

Emission credit(s) are awarded for reducing pollutant emissions thatcontribute to global warming and may, for example, be banked, traded orsold. They are conventionally expressed in the equivalent amount ofcarbon dioxide. Thus if the emission of 1 kg of R-134a is avoided thenan emission credit of 1×1300=1300 kg CO₂ equivalent may be awarded.

In another embodiment of the invention, there is provided a method forgenerating greenhouse gas emission credit(s) comprising (i) replacing anexisting compound or composition with a composition of the invention,wherein the composition of the invention has a lower GWP than theexisting compound or composition; and (ii) obtaining greenhouse gasemission credit for said replacing step.

In a preferred embodiment, the use of the composition of the inventionresults in the equipment having a lower Total Equivalent Warming Impact,and/or a lower Life-Cycle Carbon Production than that which would beattained by use of the existing compound or composition.

These methods may be carried out on any suitable product, for example inthe fields of air-conditioning, refrigeration (e.g. low and mediumtemperature refrigeration), heat transfer, aerosols or sprayablepropellants, gaseous dielectrics, flame suppression, solvents (e.g.carriers for flavorings and fragrances), cleaners, topical anesthetics,and expansion applications. Preferably, the field is ultra-lowtemperature refrigeration.

Examples of suitable products include heat transfer devices, sprayablecompositions, solvents and mechanical power generation devices. In apreferred embodiment, the product is a heat transfer device, such as arefrigeration device or an ultra-low temperature refrigeration system.

The existing compound or composition has an environmental impact asmeasured by GWP and/or TEWI and/or LCCP that is higher than thecomposition of the invention which replaces it. The existing compound orcomposition may comprise a fluorocarbon compound, such as a perfluoro-,hydrofluoro-, chlorofluoro- or hydrochlorofluoro-carbon compound or itmay comprise a fluorinated olefin.

Preferably, the existing compound or composition is a heat transfercompound or composition such as a refrigerant. Examples of refrigerantsthat may be replaced include ULT refrigerants such as R-508A, R-508B,R-23 and R-1361.

Any amount of the existing compound or composition may be replaced so asto reduce the environmental impact. This may depend on the environmentalimpact of the existing compound or composition being replaced and theenvironmental impact of the replacement composition of the invention.Preferably, the existing compound or composition in the product is fullyreplaced by the composition of the invention.

The invention is illustrated by the following non-limiting examples,with reference to the following drawings:

FIG. 1 shows a plot of R-23 concentration against capacity relative toR-508A for compositions of R-1132a, R-23 and carbon dioxide;

FIG. 2 shows a plot of R-23 concentration against coefficient ofperformance relative to R-508A for compositions of R-1132a, R-23 andcarbon dioxide.

EXAMPLES

Compositions of R-1132a, R-23 and R-116

The performance of ternary compositions of the invention are provided inthe following Tables 2 to 6, which list the volumetric cooling capacity,COP, compressor pressure ratio, compressor discharge temperature andbubble point pressure for a range of ternary compositions. The tableordinates are R-23 and R-1132a content as weight percentages with theR-116 content being inferred by difference.

TABLE 1 Cycle conditions for modelling ternary compositions Cycleconditions for modelling Condensing temperature ° C. −40 Evaporatingtemperature ° C. −85 Suction temperature ° C. same as evaporator outletIsentropic efficiency 65% Subcooling K 5 Evaporator superheat K 5Compressor clearance ratio 3%

TABLE 2 Volumetric cooling capacity in kJ/m³ R-23 content R-1132acontent w/w w/w 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 0% 542 576 607634 657 678 696 712 725 736 744 5% 566 604 638 668 695 718 738 756 771783 792 10% 589 631 668 701 730 756 778 798 815 828 838 15% 611 656 696732 763 791 816 838 856 871 882 20% 631 679 723 761 795 825 852 876 896912 924 25% 651 702 748 789 825 858 887 912 934 952 964 30% 668 722 771815 854 888 919 947 970 989 1002 35% 685 742 793 839 880 916 949 9791004 1025 1038 40% 700 760 814 862 904 943 978 1009 1036 1058 1072 45%714 776 833 883 927 967 1003 1037 1066 1089 1104 50% 726 791 850 902 948989 1027 1062 1093 1118 1134 55% 737 804 865 919 966 1008 1047 1083 11161143 60% 747 816 879 934 982 1025 1064 1101 1135 65% 755 826 891 947 9961039 1078 1115 70% 762 835 901 959 1007 1050 1088 75% 767 842 910 9681017 1059 80% 771 847 917 976 1025 85% 773 851 923 983 90% 774 854 92895% 773 855 100% 772 R-1132a content w/w R-23 content w/w 55% 60% 65%70% 75% 80% 85% 90% 95% 100% 0% 749 752 753 753 751 748 744 739 733 7265% 798 801 802 802 800 797 794 789 783 10% 844 848 849 849 847 845 841836 15% 889 893 894 894 892 890 886 20% 931 935 936 936 935 932 25% 972975 976 976 974 30% 1010 1013 1014 1013 35% 1046 1049 1049 40% 1080 108245% 1111 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

TABLE 3 Cooling Coefficient of Performance (COP) R-23 content R-1132acontent w/w w/w 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 0% 2.32 2.292.26 2.24 2.23 2.22 2.21 2.21 2.21 2.21 2.21 5% 2.32 2.30 2.28 2.27 2.262.25 2.25 2.24 2.24 2.25 2.25 10% 2.33 2.31 2.30 2.29 2.28 2.28 2.282.28 2.28 2.28 2.28 15% 2.33 2.32 2.32 2.31 2.31 2.31 2.31 2.31 2.312.31 2.32 20% 2.34 2.33 2.33 2.33 2.33 2.33 2.33 2.34 2.34 2.34 2.34 25%2.34 2.34 2.34 2.35 2.35 2.35 2.36 2.36 2.37 2.37 2.37 30% 2.34 2.352.36 2.36 2.37 2.37 2.38 2.38 2.39 2.39 2.39 35% 2.34 2.36 2.37 2.382.38 2.39 2.40 2.40 2.41 2.41 2.41 40% 2.34 2.36 2.38 2.39 2.40 2.412.41 2.42 2.43 2.43 2.43 45% 2.34 2.37 2.38 2.40 2.41 2.42 2.43 2.442.45 2.45 2.45 50% 2.34 2.37 2.39 2.41 2.42 2.43 2.44 2.45 2.46 2.472.46 55% 2.34 2.37 2.40 2.42 2.43 2.44 2.45 2.46 2.47 2.48 60% 2.34 2.372.40 2.42 2.44 2.45 2.46 2.47 2.48 65% 2.34 2.37 2.40 2.43 2.44 2.452.46 2.47 70% 2.33 2.37 2.41 2.43 2.45 2.46 2.47 75% 2.33 2.37 2.41 2.432.45 2.46 80% 2.32 2.37 2.41 2.43 2.45 85% 2.31 2.36 2.41 2.43 90% 2.312.36 2.40 95% 2.30 2.35 100% 2.29 R-23 content R-1132a content w/w w/w55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 0% 2.21 2.22 2.22 2.22 2.232.23 2.24 2.25 2.25 2.26 5% 2.25 2.25 2.26 2.26 2.26 2.27 2.27 2.28 2.2810% 2.28 2.29 2.29 2.29 2.29 2.30 2.30 2.31 15% 2.32 2.32 2.32 2.32 2.322.33 2.33 20% 2.34 2.34 2.35 2.35 2.35 2.35 25% 2.37 2.37 2.37 2.37 2.3730% 2.39 2.39 2.39 2.39 35% 2.41 2.41 2.41 40% 2.43 2.42 45% 2.44 50%55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

TABLE 4 Compressor Pressure Ratio R-23 content R-1132a content w/w w/w0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 0% 7.85 7.63 7.43 7.28 7.157.05 6.98 6.92 6.88 6.86 6.86 5% 7.87 7.65 7.46 7.30 7.18 7.08 7.01 6.956.91 6.90 6.90 10% 7.89 7.66 7.47 7.31 7.19 7.10 7.02 6.97 6.93 6.926.92 15% 7.90 7.67 7.48 7.32 7.20 7.11 7.03 6.98 6.94 6.93 6.94 20% 7.907.67 7.48 7.33 7.21 7.11 7.04 6.99 6.95 6.94 6.95 25% 7.91 7.67 7.487.33 7.21 7.12 7.04 6.99 6.95 6.94 6.95 30% 7.91 7.68 7.48 7.33 7.217.12 7.05 6.99 6.95 6.94 6.96 35% 7.92 7.68 7.48 7.33 7.21 7.12 7.056.99 6.96 6.94 6.96 40% 7.92 7.68 7.48 7.33 7.21 7.12 7.05 6.99 6.966.95 6.97 45% 7.93 7.69 7.48 7.33 7.21 7.13 7.06 7.00 6.96 6.95 6.97 50%7.95 7.69 7.49 7.33 7.22 7.13 7.07 7.01 6.97 6.95 6.98 55% 7.96 7.707.49 7.34 7.23 7.15 7.08 7.03 6.98 6.97 60% 7.98 7.71 7.50 7.35 7.247.17 7.10 7.05 7.01 65% 8.00 7.73 7.51 7.36 7.26 7.19 7.14 7.09 70% 8.037.75 7.53 7.38 7.28 7.22 7.17 75% 8.06 7.77 7.55 7.40 7.31 7.25 80% 8.107.80 7.57 7.42 7.33 85% 8.14 7.84 7.59 7.44 90% 8.19 7.87 7.61 95% 8.247.91 100% 8.30 R-23 content R-1132a content w/w w/w 55% 60% 65% 70% 75%80% 85% 90% 95% 100% 0% 6.87 6.90 6.93 6.97 7.02 7.06 7.11 7.16 7.217.26 5% 6.92 6.95 6.99 7.04 7.09 7.14 7.20 7.27 7.33 10% 6.94 6.98 7.037.08 7.13 7.19 7.26 7.32 15% 6.96 7.00 7.05 7.10 7.16 7.22 7.29 20% 6.977.02 7.07 7.12 7.18 7.24 25% 6.98 7.03 7.09 7.14 7.20 30% 6.99 7.05 7.107.16 35% 7.00 7.06 7.12 40% 7.02 7.08 45% 7.03 50% 55% 60% 65% 70% 75%80% 85% 90% 95% 100%

TABLE 5 Compressor Discharge Temperature in ° C. R-23 content R-1132acontent w/w w/w 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 0% −14.04−12.41 −11.00 −9.75 −8.60 −7.51 −6.46 −5.41 −4.33 −3.19 −1.97 5% −10.66−9.12 −7.79 −6.62 −5.53 −4.51 −3.52 −2.52 −1.48 −0.37 0.84 10% −7.32−5.87 −4.64 −3.54 −2.54 −1.59 −0.66 0.27 1.26 2.34 3.53 15% −4.00 −2.66−1.52 −0.52 0.41 1.28 2.13 2.99 3.92 4.95 6.12 20% −0.69 0.54 1.57 2.483.31 4.10 4.87 5.66 6.52 7.50 8.65 25% 2.62 3.73 4.65 5.46 6.20 6.907.58 8.29 9.07 10.00 11.12 30% 5.93 6.91 7.72 8.42 9.07 9.68 10.27 10.8911.59 12.47 13.56 35% 9.25 10.10 10.79 11.39 11.94 12.46 12.96 13.4814.10 14.91 15.98 40% 12.60 13.31 13.88 14.37 14.83 15.25 15.66 16.0816.61 17.35 18.39 45% 15.97 16.55 16.99 17.38 17.74 18.07 18.38 18.7119.14 19.80 20.80 50% 19.38 19.81 20.13 20.41 20.68 20.94 21.16 21.4021.71 22.28 23.23 55% 22.84 23.13 23.31 23.49 23.69 23.87 24.02 24.1724.39 24.82 60% 26.35 26.49 26.55 26.63 26.76 26.88 26.99 27.09 27.2165% 29.93 29.91 29.84 29.84 29.91 30.00 30.08 30.15 70% 33.58 33.4133.21 33.12 33.14 33.22 33.29 75% 37.31 36.97 36.64 36.47 36.45 36.5180% 41.12 40.61 40.13 39.87 39.81 85% 45.01 44.32 43.68 43.31 90% 48.9948.09 47.27 95% 53.05 51.93 100% 57.19 R-1132a content w/w R-23 contentw/w 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 0% −0.67 0.68 2.06 3.444.78 6.09 7.34 8.54 9.69 10.78 5% 2.15 3.53 4.94 6.35 7.73 9.08 10.3911.67 12.91 10% 4.84 6.23 7.65 9.07 10.47 11.84 13.17 14.48 15% 7.428.82 10.24 11.67 13.06 14.43 15.77 20% 9.94 11.33 12.76 14.18 15.5616.91 25% 12.41 13.80 15.22 16.63 18.00 30% 14.85 16.24 17.66 19.05 35%17.27 18.67 20.08 40% 19.68 21.09 45% 22.10 50% 55% 60% 65% 70% 75% 80%85% 90% 95% 100%

TABLE 6 Bubble Point Pressure at −40° C. in kPa R-1132a wt % R-23 wt % 05% 10% 15% 20% 25% 30% 35% 40% 45% 50% 0 540.1 579.0 610.3 635.5 655.5671.4 683.8 693.4 700.5 705.7 709.2 5% 563.4 604.1 637.2 664.0 685.6703.0 716.9 728.0 736.7 743.5 748.7 10% 584.0 626.4 661.0 689.2 712.1730.8 746.0 758.3 768.3 776.3 782.8 15% 602.2 646.1 682.0 711.4 735.5755.2 771.4 784.7 795.7 804.8 812.4 20% 618.3 663.4 700.5 731.0 756.0776.6 793.7 807.9 819.7 829.6 838.0 25% 632.4 678.7 716.8 748.2 774.1795.5 813.2 828.1 840.5 851.1 860.1 30% 644.8 692.2 731.2 763.4 790.0812.0 830.4 845.8 858.8 869.8 879.4 35% 655.7 704.0 743.8 776.7 803.9826.6 845.4 861.3 874.7 886.2 896.1 40% 665.2 714.3 754.9 788.5 816.3839.4 858.7 875.0 888.7 900.5 910.8 45% 673.4 723.4 764.7 798.8 827.1850.7 870.4 887.0 901.1 913.2 923.7 50% 680.4 731.2 773.2 807.9 836.7860.7 880.8 897.7 912.1 924.4 935.0 55% 686.5 738.1 780.7 816.0 845.3869.6 890.0 907.2 921.8 934.4 60% 691.6 744.0 787.2 823.1 852.8 877.6898.3 915.8 930.6 65% 695.9 749.0 792.9 829.3 859.5 884.7 905.7 923.570% 699.3 753.3 797.9 834.8 865.5 891.0 912.5 75% 702.1 756.8 802.1839.6 870.8 896.8 80% 704.2 759.8 805.7 843.9 875.6 85% 705.7 762.1808.8 847.5 90% 706.5 763.8 811.3 95% 706.7 764.9 100% 706.2 R-1132a wt% R-23 wt % 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 0 711.2 711.8 711.3709.7 706.9 703.1 698.1 692.0 684.4 675.4  5% 752.4 755.0 756.6 757.2757.0 755.9 754.0 751.2 747.5 10% 788.0 792.1 795.3 797.7 799.3 800.4800.8 800.6 15% 818.7 823.9 828.4 832.1 835.2 837.8 839.9 20% 845.1851.3 856.6 861.4 865.6 869.3 25% 867.9 874.8 880.8 886.3 891.3 30%887.7 895.0 901.6 907.6 35% 904.8 912.5 919.5 40% 919.7 927.7 45% 932.950% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 

TABLE 7 Pure fluid vapour pressures at this condition R23 706.2 kPaR1132a 675.4 kPa R116 540.1 kPa Maximum 706.2 kPa

Compositions of R-1132a, R-23 and R-170

The performance of ternary compositions of the invention are provided inthe following Tables 10 to 13, which list the volumetric coolingcapacity, COP, compressor pressure ratio and compressor dischargetemperature for a range of ternary compositions. The table ordinates areR-23 and R-170 content as weight percentages with the R-1132a contentbeing inferred by difference.

The cycle conditions used in the modelling are as Table 1.

TABLE 9 Reference fluid performance - pure components R170 R23 R1132aR508A Evaporator pressure bar 1.23 0.85 0.93 1.11 Condenser pressure bar7.79 7.06 6.75 8.53 Pressure ratio 6.33 8.30 7.26 7.71 Volumetricefficiency 90.9% 88.2% 87.5% 86.2% Discharge temperature ° C. 39.5 57.210.8 11.4 Volumetric flowrate m³/hr 37.3 46.7 49.6 38.5 Evaporatortemperature K 0 0 0 0.4397 glide Condenser temperature K 0 0 0 0.2223glide Volumetric capacity kJ/m³ 964 772 726 935 Cooling COP 2.32 2.292.26 2.41

TABLE 10 Volumetric cooling capacity in kJ/m³ R-170 R-23 w/w w/w 0% 5%10% 15% 20% 25% 30% 35% 40% 45% 50% 0% 726 744 761 778 794 809 823 835847 856 864 5% 789 812 834 856 877 899 919 939 958 975 991 10% 843 869895 922 948 974 1000 1026 1051 1075 1098 15% 887 916 946 976 1007 10371068 1098 1128 1158 1186 20% 923 956 989 1022 1056 1090 1125 1160 11941228 1261 25% 953 988 1024 1060 1097 1135 1173 1212 1251 1291 1329 30%977 1014 1052 1091 1131 1172 1214 1256 1300 1344 1389 35% 996 1035 10751116 1158 1202 1246 1292 1339 1387 1438 40% 1009 1050 1092 1135 11791224 1270 1317 1366 1417 1470 45% 1018 1060 1103 1148 1193 1239 12861334 1383 1434 1487 50% 1024 1066 1111 1156 1202 1249 1297 1345 13931443 1493 55% 1025 1069 1114 1160 1208 1255 1303 1351 1399 1446 60% 10241069 1115 1162 1211 1259 1308 1355 1402 65% 1021 1066 1113 1162 12121262 1311 1359 70% 1016 1062 1111 1161 1213 1264 1315 75% 1010 1056 11061159 1213 1267 80% 1002 1050 1102 1157 1214 85% 994 1042 1096 1155 90%984 1034 1090 95% 975 1026 100% 964 R-23 w/w R-170 w/w 55% 60% 65% 70%75% 80% 85% 90% 95% 100% 0% 869 871 871 867 860 850 837 820 798 772 5%1006 1018 1029 1037 1043 1049 1054 1059 1065 10% 1119 1139 1156 11721187 1203 1221 1243 15% 1212 1236 1256 1274 1291 1307 1324 20% 1292 13191341 1358 1373 1386 25% 1365 1395 1419 1435 1447 30% 1432 1470 1496 151135% 1490 1541 1576 40% 1527 1589 45% 1542 50% 55% 60% 65% 70% 75% 80%85% 90% 95% 100%

TABLE 11 Cooling Coefficient of Performance (COP) R-170 R-23 w/w w/w 0%5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 0% 2.26 2.27 2.28 2.29 2.30 2.312.32 2.33 2.33 2.34 2.34 5% 2.29 2.30 2.31 2.32 2.33 2.34 2.35 2.36 2.372.38 2.39 10% 2.30 2.32 2.33 2.34 2.36 2.37 2.38 2.39 2.40 2.41 2.42 15%2.32 2.33 2.35 2.36 2.37 2.39 2.40 2.41 2.42 2.43 2.44 20% 2.33 2.352.36 2.37 2.39 2.40 2.42 2.43 2.44 2.45 2.46 25% 2.34 2.35 2.37 2.392.40 2.42 2.43 2.44 2.46 2.47 2.48 30% 2.35 2.36 2.38 2.40 2.41 2.432.44 2.46 2.48 2.49 2.50 35% 2.35 2.37 2.39 2.40 2.42 2.44 2.46 2.472.49 2.51 2.53 40% 2.36 2.37 2.39 2.41 2.43 2.45 2.47 2.49 2.50 2.522.54 45% 2.36 2.38 2.40 2.42 2.43 2.45 2.47 2.49 2.51 2.53 2.55 50% 2.362.38 2.40 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.55 55% 2.36 2.38 2.402.42 2.44 2.46 2.48 2.50 2.52 2.54 60% 2.36 2.38 2.40 2.42 2.44 2.472.49 2.51 2.52 65% 2.35 2.37 2.40 2.42 2.45 2.47 2.49 2.51 70% 2.35 2.372.40 2.42 2.45 2.48 2.50 75% 2.35 2.37 2.39 2.42 2.45 2.48 80% 2.34 2.362.39 2.42 2.46 85% 2.34 2.36 2.39 2.43 90% 2.33 2.36 2.39 95% 2.33 2.35100% 2.32 R-23 w/w R-170 w/w 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 0%2.35 2.35 2.35 2.35 2.35 2.34 2.33 2.32 2.31 2.29 5% 2.40 2.40 2.41 2.412.41 2.42 2.42 2.42 2.43 10% 2.43 2.44 2.44 2.45 2.46 2.47 2.48 2.50 15%2.45 2.46 2.46 2.46 2.47 2.47 2.48 20% 2.47 2.47 2.47 2.47 2.46 2.46 25%2.49 2.49 2.48 2.47 2.46 30% 2.52 2.52 2.51 2.49 35% 2.55 2.56 2.55 40%2.57 2.59 45% 2.57 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

TABLE 12 Compressor Pressure Ratio R-23 w/w R-170 w/w 0% 5% 10% 15% 20%25% 30% 35% 40% 45% 50% 0% 7.26 7.28 7.30 7.31 7.33 7.34 7.36 7.38 7.407.43 7.46 5% 7.12 7.13 7.14 7.15 7.16 7.17 7.17 7.18 7.20 7.21 7.23 10%6.99 7.00 7.00 7.01 7.01 7.01 7.01 7.01 7.01 7.01 7.02 15% 6.88 6.896.89 6.88 6.88 6.87 6.87 6.86 6.86 6.86 6.86 20% 6.79 6.79 6.78 6.786.77 6.75 6.74 6.73 6.72 6.72 6.72 25% 6.71 6.70 6.69 6.68 6.67 6.656.63 6.62 6.60 6.59 6.58 30% 6.64 6.63 6.61 6.60 6.58 6.55 6.53 6.516.48 6.46 6.44 35% 6.58 6.56 6.55 6.52 6.50 6.47 6.44 6.41 6.38 6.356.31 40% 6.52 6.51 6.49 6.46 6.43 6.40 6.37 6.33 6.30 6.26 6.22 45% 6.486.46 6.44 6.41 6.38 6.34 6.31 6.27 6.23 6.20 6.16 50% 6.45 6.43 6.406.37 6.33 6.29 6.26 6.22 6.19 6.15 6.12 55% 6.42 6.40 6.37 6.33 6.296.25 6.21 6.18 6.14 6.12 60% 6.40 6.38 6.34 6.30 6.26 6.21 6.17 6.136.11 65% 6.38 6.36 6.32 6.27 6.22 6.17 6.13 6.09 70% 6.37 6.34 6.30 6.256.19 6.13 6.08 75% 6.36 6.33 6.28 6.22 6.15 6.08 80% 6.35 6.32 6.26 6.196.10 85% 6.35 6.31 6.25 6.16 90% 6.34 6.30 6.23 95% 6.34 6.30 100% 6.33R-23 w/w R-170 w/w 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%  0% 7.497.54 7.59 7.65 7.73 7.81 7.91 8.02 8.15 8.30  5% 7.25 7.28 7.31 7.357.40 7.44 7.48 7.52 7.56 10% 7.03 7.05 7.07 7.09 7.11 7.12 7.11 7.07 15%6.87 6.89 6.91 6.95 6.97 7.00 7.00 20% 6.73 6.75 6.79 6.84 6.90 6.94 25%6.59 6.61 6.67 6.74 6.83 30% 6.43 6.44 6.50 6.61 35% 6.28 6.25 6.29 40%6.17 6.11 45% 6.11 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 

TABLE 13 Compressor Discharge Temperature in ° C. R-23 w/w R-170 w/w 0%5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 0% 10.8 12.1 13.4 14.8 16.2 17.719.2 20.8 22.5 24.3 26.2 5% 13.0 14.3 15.7 17.1 18.5 20.0 21.5 23.2 24.926.7 28.7 10% 14.9 16.2 17.6 19.0 20.4 21.8 23.4 24.9 26.6 28.4 30.3 15%16.6 17.9 19.2 20.6 22.0 23.4 24.9 26.4 28.1 29.8 31.7 20% 18.1 19.420.8 22.1 23.4 24.8 26.2 27.7 29.3 30.9 32.7 25% 19.6 20.9 22.2 23.524.8 26.1 27.5 28.8 30.3 31.8 33.5 30% 21.0 22.2 23.5 24.8 26.0 27.328.6 29.9 31.2 32.6 34.0 35% 22.3 23.6 24.9 26.1 27.3 28.5 29.8 31.032.2 33.4 34.6 40% 23.7 25.0 26.2 27.4 28.6 29.8 31.0 32.2 33.3 34.535.6 45% 25.0 26.3 27.6 28.8 30.0 31.2 32.4 33.5 34.7 35.9 37.0 50% 26.427.7 29.0 30.2 31.4 32.6 33.8 35.0 36.2 37.4 38.6 55% 27.8 29.1 30.431.7 32.9 34.1 35.3 36.5 37.8 39.1 60% 29.2 30.6 31.9 33.1 34.3 35.536.8 38.0 39.3 65% 30.6 32.0 33.3 34.5 35.7 36.9 38.2 39.5 70% 32.0 33.434.7 35.9 37.1 38.3 39.5 75% 33.3 34.7 36.0 37.2 38.4 39.5 80% 34.6 36.137.4 38.5 39.6 85% 35.9 37.4 38.6 39.7 90% 37.1 38.6 39.8 95% 38.3 39.8100% 39.5 R-23 w/w R-170 w/w 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% 0% 28.3 30.6 33.0 35.7 38.6 41.7 45.1 48.8 52.8 57.2  5% 30.8 33.1 35.638.4 41.3 44.5 48.0 51.6 55.5 10% 32.4 34.7 37.2 40.0 42.9 46.0 49.252.4 15% 33.8 36.1 38.6 41.5 44.5 47.7 51.1 20% 34.8 37.1 39.8 42.8 46.049.5 25% 35.4 37.7 40.5 43.7 47.3 30% 35.7 37.7 40.5 44.0 35% 35.9 37.339.7 40% 36.6 37.5 45% 38.1 50% 55% 60% 65% 70% 75% 80% 85% 90% 95%100% 

It can be seen that by using compositions of the invention it ispossible to achieve improvements in capacity and COP compared to thepure fluid performances and also to achieve reduced compressor pressureratio. Furthermore it is possible to achieve compressor dischargetemperatures that are lower than those to be expected from use of R-508Aor R-508B.

Compositions of R-1132a, R23 and Carbon Dioxide

The performance of ternary compositions of the invention are provided inthe following Tables 15 to 18, which list performance characteristicsfor a range of ternary compositions. Plots of capacity and coefficientof performance of the compositions relative to R-508A against R-23concentration are shown in FIGS. 1 and 2.

The cycle conditions used in the modelling are as Table 1.

TABLE 14 Calculated performance of reference (r508b) and pure componentsR508A R1132a R23 Capacity relative to reference 100.0% 83.4% 79.3% COPrelative to reference 100.0% 94.2% 91.3% Discharge temperaturedifference 0.0 −3.8 46.1 (K) Pressure ratio — 7.71 6.74 8.35 Condenserglide K 0.2 0.0 0.0 Evaporator glide K 0.4 0.0 0.0 Condensing pressurebar 8.53 7.01 7.06 Evaporating pressure bar 1.11 1.04 0.85 COP — 2.412.27 2.20 Discharge temperature ° C. 11.4 7.6 57.5 Volumetric capacitykJ/m3 935 780 742

TABLE 15 CO₂ 4% 4% 4% 4% 4% 4% 4% 4% 4% 4% R23 0% 10% 20% 30% 40% 50%60% 70% 80% 90% R1132a Quantity Units 96% 86% 76% 66% 56% 46% 36% 26%16% 6% Capacity relative to 86.2% 88.2% 89.8% 90.8% 91.3% 91.2% 90.4%88.9% 86.8% 84.1% reference COP relative to reference 94.1% 94.0% 93.8%93.5% 93.3% 92.9% 92.5% 92.2% 91.8% 91.4% Discharge temperature −1.5 1.34.4 7.9 11.9 16.4 21.7 27.8 34.7 42.5 difference (K) Pressure ratio —6.8 6.8 6.9 7.0 7.1 7.3 7.4 7.6 7.9 8.1 Condenser glide K 0.4 0.4 0.40.3 0.2 0.2 0.2 0.3 0.4 0.4 Evaporator glide K 0.2 0.2 0.1 0.1 0.1 0.20.4 0.6 0.6 0.5 Condensing pressure bar 7.23 7.41 7.56 7.68 7.75 7.797.78 7.71 7.60 7.42 Evaporating pressure bar 1.07 1.08 1.09 1.10 1.091.07 1.04 1.01 0.96 0.91 COP — 2.27 2.26 2.26 2.25 2.25 2.24 2.23 2.222.21 2.20 Discharge temperature ° C. 9.9 12.7 15.8 19.3 23.3 27.8 33.139.2 46.1 53.9 Volumetric capacity kJ/m³ 806 824 839 849 854 853 845 831812 786

TABLE 16 R744 8% 8% 8% 8% 8% 8% 8% 8% 8% 8% R23 0% 10% 20% 30% 40% 50%60% 70% 80% 90% R1132a Quantity Units 92% 82% 72% 62% 52% 42% 32% 22%12% 2% Capacity relative to 88.8% 90.8% 92.3% 93.2% 93.6% 93.3% 92.3%90.6% 88.4% 85.5% reference COP relative to reference 94.1% 93.9% 93.7%93.4% 93.1% 92.7% 92.3% 91.9% 91.5% 91.1% Discharge temperature 0.8 3.77.0 10.7 14.9 19.8 25.4 31.8 39.2 47.6 difference (K) Pressure ratio —6.8 6.9 6.9 7.0 7.2 7.3 7.5 7.7 7.9 8.2 Condenser glide K 0.7 0.7 0.60.5 0.4 0.4 0.4 0.5 0.6 0.6 Evaporator glide K 0.3 0.2 0.2 0.2 0.2 0.30.5 0.7 0.7 0.5 Condensing pressure bar 7.45 7.62 7.76 7.87 7.94 7.977.94 7.87 7.74 7.55 Evaporating pressure bar 1.10 1.11 1.12 1.12 1.111.09 1.06 1.02 0.97 0.92 COP — 2.27 2.26 2.26 2.25 2.24 2.23 2.22 2.222.21 2.20 Discharge temperature ° C. 12.2 15.1 18.4 22.1 26.3 31.2 36.843.2 50.6 59.0 Volumetric capacity kJ/m³ 831 849 863 872 875 872 863 847826 799

TABLE 17 R744 12% 12% 12% 12% 12% 12% 12% 12% 12% R23 0% 10% 20% 30% 40%50% 60% 70% 80% R1132a Quantity Units 88% 78% 68% 58% 48% 38% 28% 18% 8%Capacity relative to reference 91.4% 93.3% 94.6% 95.5% 95.7% 95.2% 94.0%92.2% 89.8% COP relative to reference 94.0% 93.8% 93.6% 93.3% 92.9%92.5% 92.1% 91.7% 91.3% Discharge temperature difference 3.2 6.2 9.613.5 18.0 23.2 29.2 36.0 43.9 (K) Pressure ratio — 6.8 6.9 7.0 7.1 7.27.4 7.6 7.8 8.0 Condenser glide K 0.9 0.8 0.7 0.6 0.5 0.5 0.5 0.6 0.7Evaporator glide K 0.4 0.3 0.2 0.2 0.3 0.4 0.6 0.7 0.7 Condensingpressure bar 7.65 7.82 7.95 8.05 8.12 8.13 8.10 8.01 7.87 Evaporatingpressure bar 1.12 1.13 1.14 1.14 1.13 1.10 1.07 1.03 0.98 COP — 2.272.26 2.26 2.25 2.24 2.23 2.22 2.21 2.20 Discharge temperature ° C. 14.617.6 21.0 24.9 29.4 34.6 40.6 47.4 55.3 Volumetric capacity kJ/m³ 855872 885 893 894 890 879 862 839

TABLE 18 R744 16% 16% 16% 16% 16% 16% 16% 16% R23 0% 10% 20% 30% 40% 50%60% 70% R1132a Quantity Units 84% 74% 64% 54% 44% 34% 24% 14% Capacityrelative to reference 93.9% 95.6% 96.9% 97.6% 97.6% 96.9% 95.6% 93.6%COP relative to reference 94.0% 93.7% 93.5% 93.1% 92.8% 92.3% 91.9%91.4% Discharge temperature difference 5.5 8.7 12.3 16.5 21.2 26.8 33.140.4 (K) Pressure ratio — 6.9 6.9 7.0 7.1 7.3 7.4 7.6 7.8 Condenserglide K 1.0 0.9 0.8 0.6 0.6 0.5 0.6 0.7 Evaporator glide K 0.4 0.3 0.30.3 0.3 0.5 0.7 0.8 Condensing pressure bar 7.85 8.01 8.14 8.23 8.288.29 8.24 8.14 Evaporating pressure bar 1.15 1.16 1.16 1.16 1.14 1.121.08 1.04 COP — 2.26 2.26 2.25 2.24 2.24 2.22 2.21 2.20 Dischargetemperature ° C. 16.9 20.1 23.7 27.9 32.6 38.2 44.5 51.8 Volumetriccapacity kJ/m³ 878 894 906 912 913 906 894 876

This data shows that ternary compositions of R-1132a, R23 and carbondioxide are suitable as drop-in replacements for R-508 compositions. Inparticular it is noted that compositions including about 20 to about 60%by weight R-23 provide for both an optimised capacity, which whencombined with flammability reducing characteristics of R-23 may beparticularly desirable.

Preferences and options for a given aspect, feature or parameter of theinvention should, unless the context indicates otherwise, be regarded ashaving been disclosed in combination with any and all preferences andoptions for all other aspects, features and parameters of the invention.

The invention is defined by the following claims.

1. A composition comprising: i) 1,1-difluoroethene (vinylidene fluoride,R-1132a); ii) trifluoromethane (R-23); and iii) one or more compoundselected from hexafluoroethane (R-116), ethane (R-170) and carbondioxide (R-744, CO₂).
 2. A composition according to claim 1 comprising:v) 1,1-difluoroethene (vinylidene fluoride, R-1132a); vi)trifluoromethane (R-23); and vii) one or more compound selected fromhexafluoroethane (R-116) and/or ethane (R-170); and viii) carbon dioxide(R-744, CO₂).
 3. A composition according to claim 1 or 2 comprising: v)1,1-difluoroethene (vinylidene fluoride, R-1132a); vi) trifluoromethane(R-23); and vii) one or more compound selected from hexafluoroethane(R-116) and/or ethane (R-170); and viii) less than about 50% by weightcarbon dioxide (R-744, CO₂).
 4. A composition according to any thepreceding claims comprising from about 1 to about 98% by weight R-1132a.5. A composition according to any the preceding claims comprising fromabout 35 to about 95% by weight R-1132a.
 6. A composition according toany the preceding claims comprising from about 1 to about 98% by weightR-23.
 7. A composition according to any the preceding claims comprisingup to about 80% by weight R-116.
 8. A composition according to claim 7comprising from about 1 to about 60% by weight R-116.
 9. A compositionaccording to any of the preceding claims comprising from about 1 toabout 40% by weight R-116, from about 5 to about 98% by weight R-1132aand from about 5 to about 98% by weight R-23.
 10. A compositionaccording to claim 9 comprising from about 1 to about 30% by weightR-116, from about 20 to about 90% by weight R-1132a and from about 5 toabout 95% by weight R-23.
 11. A composition according to claim 10comprising from about 1 to about 25% by weight R-116, from about 30 toabout 80% by weight R-1132a and from about 5 to about 90% by weightR-23.
 12. A composition according to any of the preceding claimscomprising up to 40% by weight R-170.
 13. A composition according toclaim 12 comprising from about 1 to about 30% by weight R-170.
 14. Acomposition according to any of the preceding claims comprising lessthan about 10% by weight carbon dioxide, which does not contain carbondioxide.
 15. A composition according to any of claims 1 to 13 comprisingfrom about 1 to about 45% by weight carbon dioxide.
 16. A compositionaccording to claim 15 comprising from about 1 to about 30% by weightcarbon dioxide.
 17. A composition according to claim 16 comprising fromabout 1 to about 15% by weight carbon dioxide.
 18. A compositionaccording to any of claims 1 and 4 to 6 comprising about 1 to about 98%by weight R-1132a, about 1 to about 98% by weight R-23 and about 1 toabout 50% by weight carbon dioxide.
 19. A composition according to claim18 comprising about 35 to 98% by weight R-1132a, about 1 to about 60% byweight R-23 and about 1 to about 20% by weight carbon dioxide.
 20. Acomposition according to claim 19 comprising about 40 to about 60% byweight R-23.
 21. A composition according to any of claim 16 or 18 to 20comprising about 4 to about 16% by weight carbon dioxide.
 22. Acomposition according to any of the preceding claims consistingessentially of stated components.
 23. A composition according to any ofthe preceding claims which is azeotropic.
 24. A composition according toany of the preceding claims, wherein the composition is less flammablethan R-1132a alone.
 25. A composition according to claim 24 wherein thecomposition has: a. a higher flammable limit; b. a higher ignitionenergy; and/or c. a lower flame velocity compared to R-1132a alone. 26.A composition according to any of the preceding claims which isnon-flammable.
 27. A composition according to claim 26 wherein thecomposition is non-flammable at ambient temperature, preferably whereinthe composition is non-flammable at 60° C.
 28. A composition accordingto any of the preceding claims which has a temperature glide in anevaporator or condenser of less than about 10 K, preferably less thanabout 5 K.
 29. A composition according to any of the preceding claimswhich has a critical temperature of greater than about 0° C., preferablygreater than about 10° C.
 30. A composition according to any of thepreceding claims whose volumetric refrigeration capacity is at least 90%of that of R-508 at comparable cycle conditions.
 31. A compositionaccording to any of the preceding claims whose compressor dischargetemperature is within 15 K of that of R-508 at comparable cycleconditions.
 32. A composition comprising a lubricant and a compositionaccording to any of the preceding claims.
 33. A composition according toclaim 29, wherein the lubricant is selected from mineral oil, siliconeoil, polyalkyl benzenes (PABs), polyol esters (POEs), polyalkyleneglycols (PAGs), polyalkylene glycol esters (PAG esters), polyvinylethers (PVEs), poly (alpha-olefins) and combinations thereof, preferablywherein the lubricant is selected from PAGs or POEs.
 34. A compositioncomprising a stabiliser and a composition according to any of thepreceding claims.
 35. A composition according to claim 34, wherein thestabiliser is selected from diene-based compounds, phosphates, phenolcompounds and epoxides, and mixtures thereof.
 36. A compositioncomprising a flame retardant and a composition according to any of thepreceding claims.
 37. A composition according to claim 36, wherein theflame retardant is selected from the group consisting oftri-(2-chloroethyl)-phosphate, (chloropropyl) phosphate,tri-(2,3-dibromopropyl)-phosphate, tri-(1,3-dichloropropyl)-phosphate,diammonium phosphate, various halogenated aromatic compounds, antimonyoxide, aluminium trihydrate, polyvinyl chloride, a fluorinatediodocarbon, a fluorinated bromocarbon, trifluoro iodomethane,perfluoroalkyl amines, bromo-fluoroalkyl amines and mixtures thereof.38. A heat transfer device containing a composition as defined in anyone of claims 1 to
 37. 39. A heat transfer device according to claim 38wherein the heat transfer device is a refrigeration device.
 40. A heattransfer device according to claim 38 or 39 wherein the heat transferdevice comprises an ultra-low temperature refrigeration system.
 41. Aheat transfer device according to any of claims 38 to 40 wherein theheat transfer device comprises a cascade system.
 42. A sprayablecomposition comprising material to be sprayed and a propellantcomprising a composition as defined in any of claims 1 to
 37. 43. Amethod for cooling an article which comprises condensing a compositiondefined in any of claims 1 to 37 and thereafter evaporating thecomposition in the vicinity of the article to be cooled.
 44. A methodfor heating an article which comprises condensing a composition asdefined in any one of claims 1 to 37 in the vicinity of the article tobe heated and thereafter evaporating the composition.
 45. A method forextracting a substance from biomass comprising contacting biomass with asolvent comprising a composition as defined in any of claims 1 to 37,and separating the substance from the solvent.
 46. A method of cleaningan article comprising contacting the article with a solvent comprising acomposition as defined in any of claims 1 to
 37. 47. A method ofextracting a material from an aqueous solution or from a particulatesolid matrix comprising contacting the aqueous solution or theparticulate solid matrix with a solvent comprising a composition asdefined in any of claims 1 to 37, and separating the material from thesolvent.
 48. A mechanical power generation device containing acomposition as defined in any of claims 1 to
 37. 49. A mechanical powergenerating device according to claim 48 which is adapted to use aRankine Cycle or modification thereof to generate work from heat.
 50. Amethod of retrofitting a heat transfer device comprising the step ofremoving an existing heat transfer composition, and introducing acomposition as defined in any one of claims 1 to
 37. 51. A method ofclaim 50 wherein the heat transfer device is a refrigeration device,preferably an ultra-low temperature refrigeration system.
 52. A methodof claim 51 wherein the refrigeration system cools a compartment to lessthan about −70° C., preferably less than about −80° C.
 53. A method forreducing the environmental impact arising from the operation of aproduct comprising an existing compound or composition, the methodcomprising replacing at least partially the existing compound orcomposition with a composition as defined in any one of claims 1 to 37.54. A method for generating greenhouse gas emission credit comprising(i) replacing an existing compound or composition with a composition asdefined in any one of claims 1 to 37, wherein the composition as definedin any one of claims 1 to 37 has a lower GWP than the existing compoundor composition; and (ii) obtaining greenhouse gas emission credit forsaid replacing step.
 55. A method of claim 54 wherein the use of thecomposition of the invention results in a lower Total Equivalent WarmingImpact, and/or a lower Life-Cycle Carbon Production than is attained byuse of the existing compound or composition.
 56. A method of claim 53 or54 carried out on a product from the fields of air-conditioning,refrigeration, heat transfer, aerosols or sprayable propellants, gaseousdielectrics, flame suppression, solvents, cleaners, topical anesthetics,and expansion applications.
 57. A method according to claim 53 or 54wherein the product is selected from a heat transfer device, a sprayablecomposition, a solvent or a mechanical power generation device,preferably a heat transfer device.
 58. A method according to claim 57wherein the product is a heat transfer device, preferably an ultra-lowtemperature refrigeration system.
 59. A method according to any ofclaims 50 to 58 wherein the existing compound or composition is a heattransfer composition, preferably wherein the heat transfer compositionis a refrigerant selected from R-508A, R-508B, R-23 and R-13B1.
 60. Anynovel heat transfer composition substantially as hereinbefore described,optionally with reference to the examples.